Saturday, March 31, 2007

After a mild and rainy week over southern MB, Mother Nature has decided to play an April Fool's joke on southern MB with the potential for accumulating snow returning to southern MB including Winnipeg (great.. after we just got rid of it all!). A low pressure system over the Dakotas will spread an area of rain into Southern MB tonight from the south which will continue into Sunday morning with 10 mm possible. Colder air on the back side of the storm will cause the rain to change over to snow during the day Sunday, with the potential for 5 to 10 cm of snow by nightfall. Hopefully, the bulk of the precipitation with this sytem will move through as rain before the colder air moves in to change the rain to snow. If the changeover occurs earlier, or the precipitation is slower to move out, then we could see some heavy wet snow by Sunday afternoon. The good news is that temperatures are expected to remain near or just above freezing on Sunday, so there should be a lot of melting of any snow that does fall. Unfortunately this system will herald the arrival of colder air for the beginning of April, with temperatures some 5 to 10 degrees below normal through the upcoming week.

Saturday, March 24, 2007

Sunshine, southerly winds and a lack of snowcover allowed temperatures to soar over southwest MB today with temperatures reaching 19C in Melita in the extreme southwest corner of the province. Elsewhere over southwestern MB, temperatures climbed into the 10-15c range from Brandon and Dauphin through Portage to Morden. Further east however, fog and low cloud trapped in the Red River valley kept temperatures much cooler, with Winnipeg struggling to only 3C by late afternoon. Skies cleared over they city and eastern suburbs in the afternoon allowing temperatures downtown to hit +7C, but low cloud and fog persisted much of the day over the western suburbs keeping temperatures below +2c until evening.

Further west over southern SK, it was a record breaking warm day with temperatures above 20C in many localities, including a high of 23C at Coronach and Val Marie and 19.5C at Regina.

Friday, March 23, 2007

There's been a lot of bad press around here lately regarding the reliability and accuracy of EC's long range forecasts.. the latest being a less than flattering article in today's Winnipeg Free Press. This public criticism is understandable, given that EC long range forecasts lately have been giving some rather optimisticly warm forecasts in Winnipeg where there's still considerable snow on the ground. Surely EC meteorologists in Winnipeg know this and would issue more conservative forecasts to account for this, right? Well, they do, but they don't. And this is where some explanation is necessary..

Canada is a big country. Lots of territory to cover, not very many people. Like most federal departments, Environment Canada has been under tremendous pressure over the past decade or so to cut costs, and work more efficiently with fewer resources and fewer staff. The net result is that Canada now has only 7 weather offices in the country to produce every single weather forecast and warning for the entire country. The local Winnipeg weather office for example is responsible for the forecasts from southern Saskatchewan to Baffin Island. That's a huge territory for one office! Compare this to the United States, where they have over 100 weather offices for a smaller geographical area. (There are 13 offices covering Texas alone!) Obviously given such a large area to cover with such limited staff, EC has had to rely more and more on automation wherever possible, from downloading weather information on phone lines and weatheradio, to actual production of the forecasts.

As a result, weather forecasts in Canada are now automatically produced from a central supercomputer at the Canadian Meteorological Center (CMC) in Montreal. They come in two parts.. a short term forecast (today and tomorrow) and a long range forecast (Day 3,4,5) Twice a day, these forecasts are sent to the 7 regional weather offices where regional EC meteorologists start with these computer generated forecasts as a first guess. Generally, these forecasts are quite good most of the time..(most people just don't realize how good weather models have become lately.) However, regional meteorologists will adjust these computer-generated forecasts if and when necessary, based on their skill and experience. The best return on this investment of human intervention in the forecast process is in the first 24 to 48 hours, and increasingly, EC meteorologsists have been concentrating their efforts on improving the short-term forecast (i.e. today and tomorrow's weather) which has a more immediate impact on the general public. This means that the long range forecast (Day 3 and beyond) is now basically left untouched from the computer generated version sent from Montreal. In other words, local Winnipeg meteorologists are becoming less and less responsible for the content of the forecast beyond tomorrow! Now generally, these automated long range forecasts are no worse than what a human meteorologist would produce (in fact, quite often, it's better) However there are times when these forecasts can be quite poor, especially in the transition seasons of spring and fall when more variable weather and snowcover can have a tremendous impact on long range temperature forecasts (as recent forecasts have demonstrated) But regional EC meteorologists only have so much time and resources.. and increasingly, their efforts are being invested in the short-range forecast, which sometimes comes at the expense of a less accurate long range forecast. So the next time you hear that it's supposed to be 17C on the weekend, and there's still 30 cm of snow on the ground, don't blame the local Winnipeg meteorologist.. he's too busy looking at today's weather from Swift Current to Iqaluit!

More recently, the long range forecasts from EC haved been showing a warm bias due to a change in the model last year. Winnipeg meteorologists have been active in pointing out this problem to CMC headquarters in Montreal where the weather forecasts are generated from. Eventually, the model statistics will catch on to this bias and correct it, so that future long range forecasts will be more reliable temperature wise. This will be especially evident when we lose our snow cover. In the future, long range forecasts will be based on an even better forecast approach called ensemble forecasting which will be more reliable, and less prone to wild forecast swings. Still, as long as the long range forecast is totally automated, there will be occasions where the forecast will not be as accurate as the public would like. But that's the chaos of weather.. people can't expect Day 1 accuracy out to Day 5.

So there you have it.. that's why these long range forecasts are sometimes questionable (and it's not only EC.. check out Accuweather or TWN long range forecasts, they're not much better!) It's unfair to criticize local Winnipeg meteorologists for these questionable long range forecasts of late. Increasingly, it's not their responsibility, the short term forecast is. The bottom line is that you get what you pay for. If the public wants more accurate long range forecasts, then they should let their MPs know that a better funded weather service is a priority for them. In the meantime, it's always a good idea to check other sources for long range weather information (including Rob's blog!) for additional insight into future weather.

Thursday, March 22, 2007

An increasing southerly flow this weekend is forecast to spread a very mild airmass across the southern Prairies.. with double digit temperatures spreading over all areas including Southern MB. This will make a significant dent in the snowpack across southern MB over the next few days. Current forecast highs of 14C on Saturday and 17c on Sunday are likely about 5 degrees too warm for areas that are still snow covered such as Winnipeg and the Red River Valley. (Note that these extended forecasts are automated, and have been showing a 5 degree warm bias in warm southerly flows over snow covered terrain) However these higher temperatures are possible in the traditionally warmer downslope areas of southwestern MB from Dauphin to Portage and Morden where snow cover is considerably less, with bare ground becoming more evident in those areas.

Saturday will see southerly winds increasing through the day with highs of 10-14c likely over snowfree areas. Snow covered areas of the Red River valley including Winnipeg will likely be a few degrees cooler, with highs of 6-9c more likely. Saturday night will be quite mild with gusty southerly winds keeping temperatures well above freezing, with overnight lows likely not dropping below +5C. Sunday will be breezy and mild with scattered showers developing by the afternoon or evening, with even a chance for the season's first rumbles of thunder over parts of Southern MB. Highs should be 14-17c over snowfree areas, and about 10-12c for Winnipeg. The combination of sustained melting temperatures, gusty southerly winds, and increasing dewpoints will make for considerable melting of the snowpack this weekend with localized flooding possible, especially if we get some heavier shower or thunderstorm activity late Sunday.

Monday, March 19, 2007

Tuesday marks the first official day of spring, but winter was doing its best to retain its crown to the very end with another blast of cold arctic air Monday over southern MB. The Arctic high pressure system responsible for the cold blast will move off to the east tonight, with a southerly flow of milder air developing overnight. Tuesday will be a transition day over southern MB as strong southerly winds flush out the cold air that moved in today. Temperatures will gradually moderate towards the freezing mark by late in the day, however gusty southerly winds to 60 or 70 km/h will make it feel noticeably cooler. Temperatures will continue to climb Tuesday night to above freezing values, with more springlike temperatures of +7C likely on Wednesday along with lighter winds and the possibility of some rainshowers. The rest of the week looks mild and dry, with daytime temperatures above freezing every day into the weekend which should make a significant dent in the snowpack over southern MB. Temperatures will be especially mild this weekend with double digit temperatures possible over the Red River valley. Hopefully this truly marks the start of spring!

Sunday, March 18, 2007

The combination of today's rain and slushy wet snow, along with temperatures falling well below freezing tonight will produce icy roads tonight into Monday, especially untreated side roads and rural highways. The wet snow was already being compacted into a slippery layer of ice on side roads this evening, and this will become more of a widespread problem overnight as northwest winds pick up in speed, and usher in much colder temperatures.. falling to minus 15C by morning. Be prepared for slippery road conditions tonight into Monday morning, with a slower commute likely especially from areas outside the city. Hopefully road maintenance crews will be working overtime tonight to treat area roadways as much as possible by the morning commute.

Quite the roller coaster weather over the next few days as spring battles winter for control over the Prairies. For today, Winnipeg is experiencing rain for the first time this season, with temperatures of plus 1C and strong southerly winds gusting to 75 km/h. Not the nicest spring day you can get around here, but it will help reduce the snowpack. For tonight and tomorrow, much colder air will flood in from the north, with daytime temperatures back in the minus teens for Monday. That cold snap will be short lived as another strong southerly flow develops on Tuesday sending temperatures back towards freezing mark again (current forecast high of +5c on Tuesday is likely about 5 degrees too warm given the southerly flow out of a departing Arctic ridge) Milder weather can be expected from Wednesday through the rest of the week, with daytime temperatures above freezing.

Monday, March 12, 2007

Some amazing warmth over the Northern Plains and southern SK today with strong southwest winds and a lack of snow allowing record breaking temperatures in the twenties across much of the area. By mid afternoon, temperatures had cracked the 20C mark in southern SK along the US border with Coronach and Val Marie at 21c. Further south, temperatures in western ND were 22c in Bismarck, while Rapid City was an amazing 28C by 3 pm, smashing the old record for the day by a whopping 7C. Not only was this a record for the day, but it tied the all-time high for the entire month of March, set on March 26, 1993. Quite amazing considering this year's 28C reading was a full two weeks before the old mark.

Here in Southern MB, temperatures were not quite as mild due to an extensive snowpack, however an increasing southwest flow allowed temperatures to climb into the double digits from Dauphin (10c) and McCreary (14c) to Portage (11c) , while Winnipeg was struggling to reach 4C by late day.

Saturday, March 10, 2007

A strong low pressure system is forecast to move across northern Alberta into northern SK on Monday bringing a push of very mild air across the southern Prairies. Temperatures are expected to soar into the mid teens across southern SK, especially over the southwest where there is little or no snowcover. This airmass will be cooled somewhat by the time it reaches southern MB, due to an extensive snowpack over the eastern Prairies. Nevetheless, temperatures should climb to +5 to +7 in Winnipeg by late Monday even with the extensive snowpack, with double digit highs of 10-13c possible in downslope areas such as Dauphin and Portage. If it wasn't for this snowcover.. most of southern MB would have been looking at record highs in the mid teens. It's going to be even warmer to our south on Monday with highs approaching 20C in Bismarck ND, and 25C in Rapid City SD! Spring is getting closer.. slowly but surely!

Thursday, March 08, 2007

Satellite images reveal an interesting contrast in weather over the Red River valley today. Gusty southerly winds are maintaining a feed of low level cloud along the Red River valley including Winnipeg which is resulting in overcast skies and temperatures that are struggling to reach freezing. However just to the west of the Red River (west of an Elie-Gretna line), skies are sunny, which has allowed temperatures to climb to +3 in Portage and +1 in Morden. The good news is that winds in the Red River valley are expected to shift into the west tonight, which will clear out this low cloud and also allow temperatures to climb above freezing. This will lead us into a much more pleasant day Friday with sunny skies, lighter winds from the west, and temperatures of +2 to +5C. Let the melting begin!

Wednesday, March 07, 2007

Springlike weather has arrived over much of western Canada today with temperatures in the mid to upper teens over southern BC and southern AB today. Calgary was up to a balmy 15c today while Lethbridge hit 17c under sunny skies. The mild weather made it into western SK with temperatures up to 7C, but then the snowpack kept temperatures down to +4C in Moose Jaw, and -2C in Regina. This airmass is forecast to spread over southern MB Thursday into Friday, finally bringing above freezing temperatures into southern MB for the first time since early January. Look for highs of +2 to +5C over the next few days.

Tuesday, March 06, 2007

I see exceptionally mild temperatures are still forecast for Thursday, with a forecast high of +7C (up from +4C yesterday) While milder temperatures are likely for Thursday, highs of +7C are overly optimistic given that there's still 30 to 60 cm of snow on the ground throughout Southern MB and SK, and northern ND which will cool any warm sector crossing Southern MB. Looking at Thursday, the setup for an exceptionally warm day is unimpressive. A low pressure trough is forecast to lie across the MB/SK border by late Thursday, putting southern MB in a southerly flow. Southerly flows are not conducive to rapid warming in the Red River valley, especially with extensive snow cover. The best setup for warm wintertime temperatures in Winnipeg is with a westerly flow tapping milder air from southern SK and southern AB. This is not likely on Thursday. As a result, temperatures on Thursday in Winnipeg will likely only struggle up to the freezing mark, or maybe +1 or +2C at best. (Note that Accuweather and Weather Network are forecasting highs on Thursday of zero and +2C respectively. Even Grand Forks is calling for highs only around zero) I suppose with sunshine and light winds, it may FEEL like +7C, but the actual air temperature will be several degrees colder. So don't be surprised to see that forecast high of +7c drop significantly over the next day or so. (recall that for February 18th, the forecast high of +4C in the long range forecast was eventually scaled back to a high of -7C!)

Monday, March 05, 2007

Clouds have spread into southern MB late this afternoon ahead of a warm front which has brought some snow over southern SK today. Cloudy skies will persist through tonight over southern MB with some light snow spreading in from the west likely reaching Winnipeg overnight. Light snow should continue Tuesday with a cm or two possible. Temperatures shouldn't drop too much in Winnipeg tonight thanks to the cloud cover and increasing southeast winds which should actually make temperatures rise overnight. Temperatures should remain steady near the -20 mark this evening rising to -14 by morning. This weak system should clear out by Tuesday evening before another ridge builds in for Wednesday with dry and cool conditions. Milder weather is still on tap for Thursday with temperatures possibly edging above the freezing point in Winnipeg.

Sunday, March 04, 2007

It's a nice mild start today with temperatures of -3 as of 8 am this morning.. however a sharp cold front is forecast to drop through Southern MB from the north today, which will bring in gusty northerly winds and much colder temperatures. Those northerly winds will drop temperatures in Winnipeg to the minus 12 level by late afternoon.. with a forecast low of minus 26 tonight, our coldest night since mid February. Sunny skies and highs of -14 are forecast for Monday, but winds will be light which will make it feel more comfortable. The good news is this cold snap will be short lived. Milder temperatures are forecast to move in by Tuesday as a mild Pacific flow begins to bring warmer air across the Prairies from the west. However, the currrent forecast high of +8C for Thursday for Winnipeg is way too optimistic. With an extensive snowpack across the Prairies, and 50 cm of snow on the ground across southern Manitoba.. any warm sector crossing Southern MB will be cooled more than forecast models indicate. Looking at Thursday, the setup for a warm day is unimpressive. We have a weak low that is forecast to move across the Interlake, with an occluding warm sector moving across southern MB. If we can get a westerly flow on Thursday, Winnipeg may be able to hit +2 or +3C as we tap milder air from the west.. otherwise temperatures will struggle to reach the freezing mark.

Friday, March 02, 2007

The latest monthly outlooks have been issued for March, and CPC is calling for above normal temperatures over the US southwest with an equal chance of below, near, or above normal temperature for the Prairies (i.e. a non-forecast) So, in other words, there is no clear indication how March will end up temperature wise. They do show however cooler than normal weather over Alaska, with above normal precipitation over the far northern Plains. This would seem to suggest a stormy pattern for southern MB for March 2007.. with a storm track through BC and Alberta into the northern Plains bringing a greater than even chance of above normal precipitation across southern MB (mainly snow). There is also growing concensus that a La Nina will be developing over the eastern Pacific this spring, which would favour a drier than normal spring and summer over the US midwest, possibly extending into southern MB.

Thursday, March 01, 2007

I picked up another 7.4 cm of snow in Charleswood since Wednesday evening.. bringing my total snowfall since Feb 20th to 28 cm. Snow has fallen on 8 of the past 10 days here in Winnipeg.. not a lot every day, but persistent and frequent enough to add up. Snowdepth at my location is now up to 51 cm.. the deepest snow cover I've measured here in Charleswood since I started keeping records in 1998. The previous deepest snow cover I recorded was 48 cm on Jan 2 2005 after back to back snowstorms dumped 41 cm on Winnipeg.

The good news is that it looks like we're finally going to get into a drier weather pattern over the next few days with no additional snowfall expected from Friday into early next week. A good chance to finally clean up some of this snowfall!